The invention relates to an expandable dowel or expandable bolt for insertion into a borehole in the masonry or the like.
A prior proposed expandable dowel comprises an expanding sleeve with multiple slots extending from the one end thereof, the slotted portion being expandable by at least one conical expanding member which engages into the slotted end of the sleeve. A screwthreaded bolt extends through the expanding sleeve and is in screwthreaded engagement with the expanding member and has a shaft which is provided with a spacer sleeve adjoining the unslotted end of the expanding sleeve, said spacer sleeve being retained on the screwthreaded bolt by the bolt head or by a nut screwed upon the screwthreaded bolt with an interposed washer. In utilising such a prior proposed dowel, the object to be supported is clampable between the underside of the bolt head or washer and masonry or the like in which a borehole has been formed, the dowel being inserted in the borehole.
Expandable dowels of this kind are used, for example, for mounting items such as a metal plate on a solid wall or the like by insertion of the dowel in a bore in the wall, the dowel also passing through a bore in the specific item. The bores are sufficiently large to ensure that the expandable dowel can be inserted through the aligned bores until the washer or the bolt head abuts on a surface of the item after the item is placed on the wall in the intended mounting position. Rotation of the bolt head or of the nut by means of a suitable tool draws the expanding member into the slotted end of the expanding sleeve so that by said sleeve expands and thus the dowel is anchored in the bore provided in the wall at a depth defined by the length of the spacer sleeve and the expanding sleeve. Since the bolt head or nut can be tightened only until it abuts on the outer endface of the spacer sleeve whose inner endface engages with the expanding sleeve, it is possible that even powerful tightening of the bolt head or of the nut does not permit the item to be anchored sufficiently firmly on the solid wall because no further movement of the bolt head or nut is permissible after the washer or bolt head engages with the spacer sleeve.